Grease composition

ABSTRACT

A grease composition consists of a lubricating base oil thickened e.g. to a penetration value of above 310, by a mixture of atactic polypropylene of Melt Viscosity Index above 50 and a polyethylene preferably a high density polyethylene.

United States Patet [1 1 Dodson et al.

[4 Nov. 26, 1974 GREASE COMPOSITION Inventors: Stanley Charles Dodson,

Leatherhead; Robert Henry Newman, Weybridge, both of England Assignee: The British Petroleum Company Limited, London, England Filed: Nov. 27, 1972 Appl. No.: 309,680

Foreign Application Priority Data Nov. 29, 197] Great Britain 55306/71 us. Cl. 252/59 1m. (:1. ..C10m 5/10, ClOm 7/14 Field of Search 252/59, 56 S [56] References Cited UNITED STATES PATENTS 3,290,244 12/1966 Polishuk e12 al. 252/59 3,392,119 7/1968 Mitacek 252/59 Primary Examiner-Daniel E. Wyman Assistant Examiner-I. Vaughn Attorney, Agent, or FirmMorgan, Finnegan, Durham & Pine [57] ABSTRACT 5 Claims, No Drawings l GREASE COMPOSITION This invention relates to a polymer-thickened grease composition more particularly it relates to a polyolefinthickened grease composition.

It is knownto thicken lubricating oils into greases using particular polyethylenes, either alone or in admixture with other thickeners such as alkali metal soaps, e.g. as described in UK Patent No. 986192.

We have found that greases thickened by polyethylene tend to have a grainy structure which is very dif-.

ficult to convert to a smooth grease, and more satisfactory greases can be formed by use of a mixture of olefin or one which can be easily smoothed, so the choice of ,ylene is preferably 1:1 to 10:] more preferably 2:1 to

The grease compositions of the present invention preferably have a penetration above 300, more preferably of 310-500.

The penetration of the greases can be measured by Test Method ASTM 217-68.

The invention will now be described with reference to the following Example.

EXAMPLE Greases were prepared from two different lubricating base oilsby heating halfthetotal quantity ofoil and the polyethylene to C. The ataetic polypropylene was slowly added whilst heating to C. mins.

The batch was held at 150C for 1 hour, to allow the t polymers to swell and partially dissolve. The batch was heated to C and held at this temperature for at least 30 mins to give a complete solution of the polymers. The rest of the lubricating oil was added and the batch cooled as quickly as possible to form a grease. The grease was circulated through a homogeniser at 80C to give a smooth grease.

Tables I and 2 give information on the materials used in the forming of greases in Table 3. Table 4 shows'the effect of Melt Index on Grease Structure.

in the Tables, smooth means a grease having a smooth consistency and is substantially homogeneous, grainy meanshaving the appearance of grains or particles in the grease, and rubbery means a more cohesive and spongy or elastic structure than the well known buttery structure of most lubricating greases. In addition removing some of such a grease from the bulk forms strings still attached to the bulk of the grease, the strings having elastic properties.

TABLE 1 DATA ON POLYM ERS Trade Melt Density Molecular Polymer Type Name Grade lndex g/ml weight Atactic Polypropylene B 0 20 0 20 0.87 9,000ll0,000

20 50 20 50 0.87 (lsotactic 50 50 0.87 content about 671 Polyethylene ll Rigidex XGR 369 0.96 150,000 lll do. Type 9 0.9 0.96 38,000 lV do. Type 50 5 0.96 I 70,000

Melt Index: BS 2782. Mflht1d 1050 for polyethylene ASTM D 1238 for polypropylene at C Molecular Weight: Intrinsic viscosity method Density: BS 2782, Method 509A rained by.Test Method BS 2782, Method 105 c or ASTM D1238. The molecular weight of the polypropylene is preferably below 100,000.

- Preferably the molecular weight of the polyethylene is from 20,000 to 500,000 weight average, more preferably from 50,000 to 250,000.

The total weight of polymer in the grease is preferal-20f/r, more preferably 3-157! based on the total weight of the composition.

lhe weight ratio ofatactic polypropylene to polyeth- TABLE 3 Atactic Polyethylene Total Polypropylene Grease Oil Polypropylene Polymer :Polyethylene orked Ref. Type (B) 7!. wt Type "/1 wt 7: wt Ratio Pen. Structure* Notes 4/1663 Y 4.20 11 0.80 5.00 5.25 z 1 411 Sl.G.Sl.R Grease can be smoothed, 4/1663A 3.93 11 0.75 4.68 5.25 l 441 Sl.G.Sl.R SLR 4/1661 Y 4.20 111 0.80 5.00 5.25 1 442 51.0 Grease can be smoothed 4/1660 Y 4.20 [V 0.80 5.00 5.25 l 436 SM 4 /1 6595 A H g 393 IV 0.75 4.68 5.25 1 1 445 SM 1/1739 2 9.98 11 1.98 11.96 l 401 G.Sl.R Grease can be smoothed, 4/1668 7.43 11 1.48 8.91 5 l 410 G.Sl.R still 4/1668A 5.81 11 1.16 6.97 5 1 473 G.Sl.R Sl.R

4/1669 Z 8.75 111 1.75 10.50 5 1 l 372 G Grease can be smoothed, 4/1669A 7.66 111 1.53 9.19 5 l 411 G with some 4/16693 7.17 lll 1.43 8.60 5 I l 443 CI difficulty 1/1751 Z 1001 IV 1.98 11.99 5 1 420 81.0 Grease can be smoothed, 4/1667 8.75 [V 0.75 10.50 5 1 431 51.6 easily 1/1778 7.53 [V 3.67 11.00 2: l 401 S1.G

' NOTES:

SM Smooth G Grainy R Ruhhery S1 Slightly TABLE 4 EFFECT OF MELT 1NDEX Grease Oil Atactic Polypropylene Worked Ref. Type Type B Pen. Structure Notes Melt Index 7r wt Range 4/1629 Y 0 5.50 373 GR Very difficult to smooth 4/1629A 0 20 4.40 436 GR grease 4/1630 20 5.50 436 Sl.G.R Grease can be smoothed 4/1631 50 5.50 443 SLR 4/1657 50 v 7.20 438 SLR 4/1633 Z 0 20 15.00 173 Vy.G.R Extremely difficult to 4/1633A 0 20 9.40 364 Vy.G.R smooth grease 4/1634 2Q: 50 15.00 398 Sl.G.R v Grease can be smoothed 4/1634A 20 50 11.30 440 S1.G.R with some difficulty 4/1635 50 15.00 420 SLR Grease can be smoothed 4/1454 50 12.00 428 SLR NOTES:

S1 Slightly G Grainy Vy Very R Robbery A We claim: 2. A grease composition as claimed in claim 1 in l. A grease composition which consists essentially of a lubricating base oil thickened to a grease consistency with from 1 to 20% weight of a polymer mixture, said polymer mixture consisting of an atactic polypropylene of melt index above 50 and a molecular weight below 100,000, and a polyethylene of density above 0.94 grm- /cc and molecular weight of 20,000 to 500,000, the weight ratio of said atactic polypropylene to polyethylene being from 1:1 to 10:1.

which the weight ratio of atactic polypropylene to polyethylene is from 2:1 to 5:1.

3. A grease composition as claimed in claim 1 in which the polyethylene has a molecular weight of 50,000 to 250.000.

4. A grease composition as claimed in claim 1 which has a penetration above 300.

5. A grease composition as claimed in claim 1 which has a penetration of 310 to 500.

WA PATENT OFFICE clm'mwmww F @RECTmN mm N0. 3,850,828 m fiecember 11 1974 Stanley Charlw Dadsofi a Robert Henley Newman Inventor a the ahovm-idmflfiafl patent It: is certifie that @TI'OT appwm in & as?) wavy m heinm and that said Lettem Katmai: we hex-may ammmm Column 2, line 15 please delete ruins. Column 4, line 5, in Table 3 the subtitle "arksad Pen." should read Worked Pen.

Signed and sealed this 28th day of January 1975.

(SEAL) Attes't:

MCCOY M. GIBSON JR. 0. MARSHALL DANN Attescing Officer Commissioner of Patents 

1. A GREASE COMPOSITION WHICH CONSISTS ESSENTIALLY OF A LUBRICATING BASE OIL THICKENED TO A GREASE CONSISTENCY WITH FROM 1 TO 20% WEIGHT OF A POLYMER MIXTURE, SAID POLYMER MIXTURE CONSISTING OF AN ATACTIC POLYPROPYLENE OF MELT INDEX ABOVE 50 AND A MOLECULAR WEIGHT BELOW 100,000, AND A POLYETHYLENE OF DENSITY ABOVE 0.94 GRM/CC AND MOLECULAR WEIGHT OF 20,000 TO 500,000, THE WEIGHT RATIO OF SAID ATACTIC POLYPROPYLENE TO POLYETHYLENE BEING FROM 1:1 TO 10:1.
 2. A grease composition as claimed in claim 1 in which the weight ratio of atactic polypropylene to polyethylene is from 2:1 to 5:1.
 3. A grease composition as claimed in claim 1 in which the polyethylene has a molecular weight of 50,000 to 250,000.
 4. A grease composition as claimed in claim 1 which has a penetration above
 300. 5. A grease composition as claimed in claim 1 which has a penetration of 310 to
 500. 